title: Analysis of factors influencing pancreatic beta-cell function in Japanese patients with type 2 diabetes: association with body mass index and duration of diabetic exposure.
abstract: OBJECTIVE
  To elucidate the clinical factors affecting beta-cell function, serum C-peptide immunoreactivity (CPR) levels of patients with type 2 diabetes were analyzed.
  
  
  METHODS
  Seven hundred Japanese patients with type 2 diabetes were enrolled. beta-Cell function was evaluated by fasting CPR (FCPR), 6 min after intravenous injection of 1mg glucagon (CPR-6 min), and the increment of CPR (DeltaCPR). Simple regression analysis between FCPR, CPR-6 min, and DeltaCPR and measures of variables and stepwise multiple regression analysis were carried out.
  
  
  RESULTS
  Years from diagnosis and BMI were the major independent variables predicting beta-cell function. Years from diagnosis was negatively correlated with CPR-6 min (P<0.0001, r=-0.271), and decrease in CPR-6 min was 0.050 ng/(ml year). BMI was positively correlated with CPR-6 min (P<0.0001, r=0.369). When subjects were divided according to BMI, the decrease in CPR-6 min per year in the high-BMI group (0.068 ng/(ml year)) was greater than that in the low-BMI group (0.035 ng/(ml year)).
  
  
  CONCLUSIONS
  A linear decline in endogenous insulin secretion over more than several decades of diabetes was confirmed by this cross-sectional study. The duration of diabetes exposure and BMI are thus major factors in beta-cell function in Japanese patients with type 2 diabetes.
authors.affiliation: Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Funakoshi
authors.forename: Shimpei
authors.initials: S
authors.lastname: Fujimoto
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hamasaki
authors.forename: Hideya
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Fujita
authors.forename: Kaori
authors.initials: K
authors.lastname: Ikeda
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hamamoto
authors.forename: Masaya
authors.initials: M
authors.lastname: Hosokawa
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Seino
authors.forename: Nobuya
authors.initials: N
authors.lastname: Inagaki
mesh_terms: D044466:Asian People; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism* / Q000502:physiology; D008875:Middle Aged; D012044:Regression Analysis; D013997:Time Factors
chemical_list: D002096:C-Peptide; D007328:Insulin